Traditionally, when refrigerant charged refrigeration systems were repaired, the refrigerant charge was simply loosed to the atmosphere as necessary to accomplish the repairs. In recent times, it has become increasingly desirable to capture and reuse the refrigerant charge in these units for two reasons; refrigerant pollution of the atmosphere is perceived as environmentally destructive and the cost of refrigerant materials has increased making the disposal and replacement of the refrigerant charge increasingly costly.
Refrigerant recovery devices of the prior art have compressed and cooled refrigerant from charged systems to a liquid state for storage and reintroduction to the same system after repair has been accomplished or for use in other systems. Many of these prior art recovery systems have employed filtration of the refrigerant during the removal-compression-cooling process to remove contaminants from the used refrigerant. However, devices of the prior art have not provided for the systematic removal of "incompressible" gas contaminants, i.e. gasses much less compressible than the refrigerant, such as air, from the used refrigerant during the recovery process.
Also, under certain conditions of sufficiently high refrigerant pressure and cool ambient temperatures, some of the prior art systems are susceptible to entry of liquid refrigerant into the suction side of the recovery system compressor which may cause damage to the compressor and power components of the recovery system.
Further, many of the prior art systems may operate satisfactorily only in a limited range of ambient temperature and cannot effectively remove energy from the compressed refrigerant to assure its complete liquification prior to its injection into a storage container when ambient temperatures are very high. Other of the prior art recovery devices may achieve acceptable performance during recovery operations over a wide range of ambient temperatures, but at a concomitant increase in recovery system production cost that makes them economically impractical for purchase by operators providing repair services in any but the most extreme environments.
Many units of the prior art have been of such high cost as to make capture, purification and reintroduction of the refrigerant charge to refrigeration units under repair of questionable economic justification, even in a political climate of increasing environmental concern.